Felix Salmon draws my attention t some recent work by Nathan Berg on the lack of proper grocery stores in poor neighborhoods. As Berg has it, the crux of the matter isn't that executives look at the idea of putting a supermarket in the poor neighborhood and then reject that option. Rather, they rely on the absence of stores in neighborhoods like that as a heuristic and the option never even gets to the analysis stage.

If that's true, of course, then there may be a lot of money sitting on the table for an enterprising sort somewhere to make and the question becomes why nobody's trying to fill that niche.